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We tried to fabricate a strain sensor element using magnetostrictive film on a Si wafer for realizing microelectromechanical systems (MEMS) applications. The principle of the sensor is based on the inverse-magnetostriction effect. In our previous study, the same sensor element on thin conventional glass substrate exhibited ultrahigh sensitivity as a strain sensor due to well-induced uniaxial magnetic anisotropy to the width direction of rectangular FeSiB layers. The uniaxial anisotropy was realized by residual stress among FeSiB, molybdenum as conductive layer, and the substrate after field annealing. However, contrary to the previous results, in this paper, by utilizing Si wafer for the substrate, it was found that uniaxial anisotropy of the rectangular FeSiB layer was induced to the longitudinal direction. The reason of the result was due to the large difference of the coefficient of thermal expansion between the thin glass substrate and Si wafer. Therefore, rotation of magnetic moment of the FeSiB layer from the longitudinal direction to the width direction by applying compressive stress was observed by magnetic Kerr effect microscopy. The results indicate that the sensor element on the Si wafer will have suitable properties as MEMS-type strain sensor. [ABSTRACT FROM AUTHOR]

The thin-film type giant magnetoimpedance (GMI) sensor has generated substantial interest owing to its advantages, including ease of integration and greater potential for size reduction. Controlling the magnetic anisotropy is a requirement for developing the high-sensitivity GMI sensor. In this paper, we examined the influence of various sensor geometries on magnetic anisotropy, while also considering the demagnetizing factor. Transverse magnetic anisotropies were induced in all sizes of the sample. The induced magnetic anisotropies were well defined along the transverse direction, with only a little closure domain. The induced magnetic anisotropy was dependent on the width of the sensor and it was sensitively rotated according to the increase in the width of the sensor. [ABSTRACT FROM AUTHOR]

This paper introduces an in-plane uniaxial anisotropy control method of Fe72Si14B14 magnetostrictive thin-film for high sensitivity of MI sensor. The anisotropy can be controlled by inverse-magnetostriction and inducing a bias stress using the difference of thermal expansion coefficient in bimetal structure. We can control the uniaxiality of anisotropy by the structure of the thin-film. Our proposed methods are useful in solving the problems and inconveniences of existing methods. To verify the proposed methods, we carried out experiments as well as FEM simulation. Looking at the FEM simulation and magnetic domain observation results, we confirmed that the in-plane uniaxial anisotropy could be controlled by a difference of a thermal expansion coefficient. Moreover, changes in the length of the conductive layer provides the local (edge section) control of the uniaxial anisotropy. [ABSTRACT FROM AUTHOR]